The solar power source of the present invention is particularly suitable for powering outdoor advertising signs of the type and in a manner described in pending U.S. Application No. 90,322, filed Nov. 1, 1979, for Solar Powered Lighting System, by Edward J. Stackpole. Generally, however, the solar power source of the present invention would have application in any environment where a constant power source were desired. Because the present primary application of the herein described invention is for powering outdoor advertising signs, however, the invention will be described in conjunction therewith for explanatory purposes only.
Illuminated outdoor advertising signs have traditionally been powered by connection to the local electrical utility service. That involves, of course, hiring an electrician to make the appropriate electrical connections to such signs and also involves the recurring monthly charge for electricity used. It is desirable for both environmental and economic reasons to use an alternative to commercially produced electricity. Solar power offers such alternative.
Previous attempts at solar powered signs, however, have involved taking the low voltage output of photovoltaic panels and converting that low voltage to a higher voltage in order to power conventional illumination sources. As described more fully in the above referenced application, such attempts have generally failed because the voltage conversion involves energy loss and concomittant inefficiency. The above referenced application solves that problem by using a sign capable of being operated at low voltage. For example, a sign illuminated with light emitting diodes requires the same low voltage generated by conventional photovoltaic panels. That type of system is inherently more efficient because voltage conversion is not required.
The present invention consists of a solar power source designed to operate such a low voltage sign. Because the solar power source is entirely self-contained, no connection to a local electrical utility service is necessary and of couse no commercially produced electricity need be used.
Lastly, the electronic control of the present invention is capable of sensing a drop in battery voltage and operates to turn the powered device off until the battery is recharged thereby avoiding excessive battery discharge.